A Fair Work Australia (FWA) report has found former Labor MP turned crossbencher Craig Thomson used work credit cards to pay for escort services while he was national secretary of the Health Services Union (HSU).

A senate committee has published the 1,100-page report after being handed the document by FWA this afternoon.

The report found more than 150 breaches of union rules by Mr Thomson, including that he spent almost $6,000 using union credit cards on escort services while he was travelling away from home and staying in hotels.

The report says the money was spent either for Mr Thomson's benefit or that of someone else.

It also details almost $270,000 in spending on activities connected to helping Mr Thomson win his seat in parliament.

And it outlines a breach of union rules by both Kathy Jackson, the union's current national secretary and Michael Williamson, its suspended national president.

She said the FWA investigation revealed an organisation that abjectly failed to have adequate governance arrangements in place to protect union members' funds against misuse.

"I have decided that the public interest strongly favours acting wherever possible to ensure that organisations and their officers and employees are properly held to account for the expenditure of the union's funds," Ms O'Neill said in a statement.

Mr Thomson then issued his own statement denying any wrongdoing and criticising the report as biased and unfair.

"Any proceedings brought against me in respect of the findings in the report will be strenuously defended," Mr Thomson said.

"This whole investigation has been nothing short of a joke.

"It is unprecedented that an investigative body has such little confidence in its report that it seeks parliamentary privilege as a condition of the report's release."

Mr Thomson said both the Commonwealth Director of Public Prosecutions and police had made it clear that there was nothing in the report of a criminal nature.

Opposition frontbencher Eric Abetz says HSU members will be horrified by the FWA findings.

"[Prime Minister Julia Gillard] I think needs to seriously contemplate, in fact she should reject Mr Thomson's vote in the Parliament, because it is now under such a cloud to have her Government's legislative program get through on the basis of Craig Thomson's vote," he said.

FWA had already sent the results of its three-year inquiry to the CDPP, which has now handed the document to the Victorian and New South Wales police.

Federal Workplace Relations Minister Bill Shorten admits the investigation has taken too long and has announced that the Government will introduce changes to give FWA more power.

"Australians should have confidence that any allegations of breaches of the law will be investigated quickly. The actions I'm announcing today will ensure that this delay does not happen again," he said.

He says people should not think that all unions have the same problems.

"I just don't want to let a few rotten apples, some parts of the Health Services Union, become a smear across all unions," he said.

"I've been speaking with the incoming head of the ACTU, Dave Oliver. He's as committed as I am to the lessons and that we improve governance."